This is one of the best survey histories that I have ever read: while comprehensive, it neither gets bogged down in obscure scholarly debates nor over-simplifies controversies on sources or interpretation for lay readers. I was utterly absorbed in it for weeks - every page made me want to learn more in more specialized sources. A demanding read, its level is advanced undergraduate or early graduate school.
The book starts with the sudden deterioration of the West Roman Empire, with a detailed portrayal of the culture, the military challenges faced, and an extended analysis of the collapse. This takes up the first 100 pages and is necessary for an understanding of the new order (or disorder) that is covered in the next 300+ pages. In seeking causes of the implosion, the author examines the thesis that it was Christianity, population decline, or circumstances and bad decisions; it is a wonderfully nuanced discussion.
The last 3/4 of the book covers both the rise of new states or kingdoms as well as the rise of Christianity and its institutions, which differed in many ways from the Roman ones that carried on through the cultural influence of surviving aristocrats. This is so dense with ideas and information that I cannot do justice to it here. Essentially, new kingdoms arose that borrowed from Roman models of government, culminating in the Holy Roman Empire of Charlemagne. However, with the exception of Byzantium, these arrangements were temporary hereditary monarchies, rarely intact for longer than 100 years due to incessant wars with eachother or with outside forces (Arabs, Slavs, Vikings, all of which is covered). The greatest change was the development of a Christian ideology as a way to transmit culture and ultimately political reach.
There are faults with the book. First, there is only one map, which is a serious problem given the complexity of evolving regions with names that were long superceded - would you know, for example, what part of Germany was "saxon"? Second, there are no illustrations, which would have enhanced the reading experience. Third, there is no wrapup analysis at the end - it just ends abruptly, with a descriptions of the Ottonians' demise. You get no view of what follows, what it might have meant, and what was accomplished. Finally, social questions, economics, and technology are not covered.
Recommended for all serious students of history. It is a wonderful read and beautifully written.